Bone induction in an alloplastic tray

ABSTRACT

A non-metallic mesh bone induction tray readily contoured, trimmed and implanted during only one surgical procedure. The tray&#39;&#39;s hollow center passage is for containment of particulate bone graft. Pores penetrating the tray&#39;&#39;s thickness allow tissue fluids access to the particulate graft material.

United States Patent [191 Leake et al.

1451 Nov. 26, 1974 BONE INDUCTION IN AN ALLOPLASTIC TRAY the Los Angeles County Harbor General Hospital, Torrance, Calif.

22 Filed: -Nov. 1,1972

21 Appl. No.: 302,903

[52] U.S. Cl. 3/1, 128/92 C, 1 28/92 G [51] Int. Cl. A6lf 1/24 [58] Field of Search 3/1, DIG. 1; 1223/92 C, 128/92 CA, 92 R, 92 BC, 92 D, 92 G, 1 R, 334 R; 32/10 A [56] References Cited I UNITED STATES PATENTS 943,113 12/1909 Greenfield 32/10 A 3,304,557 2/1967 Polansky 128/334 R 8/1969 Schmitt et al 129/334 R 3,514,791 6/1970 3,562,352 2/1971 3,707,006 12/1972 OTHER PUBLICATIONS Vitallium Surgical Appliances (Catalog), Austenal Co., New York, N.Y., 1964 p. 57, Mandibular Reconstructive Appliances, No. 6914 (Conley Type) relied upon.

Primary ExaminerRichard A. Gaudet Assistant Examiner-Ronald L. Frinks Attorney, Agent, or FirmAllan Miller [5 7 ABSTRACT A non-metallic mesh bone induction tray readily contoured, trimmed and implanted during only one surgical procedure. The trays hollow center passage is for containment of particulate bone graft. Pores penetrating the trays thickness allow tissue fluids access to the particulate graft material.

5 Claims, 3 Drawing Figures BONE INDUCTION IN AN ALLOPLASTIC TRAY BACKGROUND OF THE INVENTION trauma, congenital malformations, ablative surgery, or

even malignant diseases, such as cancer. However, os-

seous defects in facial bones are particularly difficult to.

repair. This results primarily from a loss of intrinsic tissue, or a lack thereof; and because of the necessity of more exacting visual and cosmetic requirements.

Of all the facial bones, perhaps, the most difficult to repair is the mandible since the changes in contour are more distinct; and the mandible is more stress bearing. Proper bone healing depends upon absolute stability and adequate osteogenic potential. When the defect is too large to repair withfixation, grafting must be done. Solid autologous bone grafts, usually of the iliac crest, rib, metatarsal, or tibia have been used for repairing large discontinuity defects of the mandible.

However, shortcomings, in conventional methods, have included difficulty in adapting the bone to facial contours and irregular remodeling when the new host bone is formed with consequent foci of decreased resistance to compressive and tensile forces. Further problems include being subject to resorption and to fracture. As a consequence, reconstruction surgeons have sought other techniques, which are still not nearly as suitable and as expedient as the proposed invention. It has been shown that osteogenesis can occur with fresh autologous bone chips as a particulate graft; however, a framework must be provided to contain the bone chips and assure stability.

Bone induction trays have been used for immobilization of mandibular defects and containment of particulate bone grafts; however, those trays were fabricated of metal including titanium or chrome-cobalt alloys. These trays were somewhat unsatisfactory for a number of reasons. First, using such a tray necessitated an additional surgical procedure prior to the implant operation to derive a mold of the patients mandible, from which mold the metallic tray is custom fabricated. The non-ductile metal tray must be fabricated with great precision since it cannot be readily altered or adapted at the operating table. Ductile metals have been considered for this use, but have been found to be poorly tolerated in the biological environment.

Since the conventional metallic tray was unsatisfactory and inadequate, the need for a novel type of tray had long existed; however, the solution to the problem was not obvious to those skilled in the art of surgical reconstruction of osseous defects.

As will be seen, the proposed invention, in addition to being non-obvious, has numerous advantages over bone induction trays used in the prior art. The alloplastic tray makes it possible to reconstruct osseous contour defects, specifically the mandible, simply and aesthetically. In addition, the alloplastic tray can be made in large numbers quite inexpensively and thus results in a savings in costs over the production of conventional trays.

It will be understood that wherever the term alloplastic is used herein, this denotes a non-metallic composition.

Perhaps the most outstanding feature of this novel invention is that it eliminates the necessity for at least one surgery, and the risks, costs and inconvenience associated therewith; since the final contouring and customizing of the alloplastic tray to the requirements of the surgical site can be accomplished at the operating table using only scissors for trimming and shaping the tray. This gives the surgeon greater flexibility in adapting a suitable implant to the patient in a simple and effective manner. Thus with this novel device, only one operation is required at the time of the actual implant. However, with conventional trays, three operations were sometimes necessary: One operation to construct a mold from the surgical site. A second operation to implant the tray which because of its extreme rigidity and inflexibility could not be contoured at the time of implant, and a third operation to remove the metal tray SUMMARY OF THE INVENTION The invention comprises a porous, hollow mesh tray, of non-metallic construction, to be used for bone induction. The non-metallic or alloplastic tray is easy to fabricate and contour and is well tolerated in the biological environment. After a standard mold of a predetermined size, shape and contour has been made, the

' tray canbe finally contoured and customized at the operating table using only scissors for trimming and shaping. This gives the surgeon greater flexibility in adapting a suitable implant to the patient simply and effectively. It will be seen in the preferred embodiment that the alloplastic tray used to hold a particulate bone graft is made of either Dacron or Nylon mesh impregnated with a polyether urethane elastomer. However, it should be noted that other plastic or non-metallic materials may be used in this novel manner.

The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an overall perspective view of the novel, hollow mesh tray, particularly adaptable for mandibular reconstruction.

FIG. 2 is a cross-sectional view of the structure shown in FIG. 1.

FIG. 3 is an overall perspective view of the novel tray, adaptable for reconstruction of long bones, not having the contours and stress bearing characteristics of the mandible.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in this case, and particularly to FIG. 1, it may be seen that the invention contemplates and includes a non-metallic hollow mesh tray, particularly adaptable for mandibular reconstruction, generally designated by reference numeral 10.

Although the non-metallic or alloplastic tray 10 may have a wide variety of cross-sectional forms or shapes, the preferred embodiment for mandibular reconstruction is seen in FIG. 1 wherein tray has a shape simulative of the mandible.

The body of the mandible reconstruction tray is simulative of the body of a mandible, and is intermediate two opposing ends 16 and 17, simulative of the ascending ramii. Furthermore, it may be seen that the tray 10 has a buccal aspect 25, opposite the lingual aspect 35; and a superior aspect 45, opposite the inferior aspect 55, as does a mandible.

As seen in FIG. 1, top end 26 and bottom end 27 of the buccal aspect may be in close juxtaposition relationship to one another to form a narrow slit or space gap 28 between said juxtaposed ends along the buccal aspect and coextensive therewith. It is most significant that if there is a slit or space gap 28, said slit must be along the buccal aspect. The purpose of the slit is to provide an opening through which the bone chips may be inserted by forceps or otherwise. The chips are placed in close proximity with one another and with the bone ends.

If the slit were along the superior aspect 45, the contact of the chips with the gingival tissue would cause errosion of said tissue, since forces of mastication would make the implant tray dehisce through the gingival or mucosal tissue. In addition, insertion of the bone chips is, of course, much easier through the buccal aspect; and the buccal aspect is least susceptible to trauma or aggravation.

Alternatively, ends 26 and 27 may be shown as abutting each other, since the ends must be sutured together after the insertion of the bone chips.

As may be seen from FIG. 1, tray 10 has an elongate hollow center passage or void 50, coextensive therewith, which is subsequently filled with the bone graft material.

Penetrating the entire thickness of the material of which the tray is composed are a plurality of voids or apertures, collectively referred to as 40, which function as pores.

It is essential that the tray be porous to allow the tissue fluids easy access to the particulate graft material.

As shown in FIG. 2, for purposes of illustration, the pores are substantially elliptical in shape; however, the pores may be circular, square, or of any shape. The pores may vary in size and may be in any spaced apart relationship.

The ultimate objective is to achieve optimum porosity consistent with rigidity and immobilization of the bone ends. The pores need not be coextensive with the entire length of the tray, as long as there is sufficient porosity in the area of the tray in which the new bone is to grow. Consequently, a tray might be porous in the middle but not at its ends, depending upon the particular requirements involved.

FIG. 3 illustrates another embodiment of this novel invention, specifically adaptable for long bone reconstruction. This tray, generally designated by reference numeral 60 is substantially tubular or cylindrical in shape. It has a substantially circular outer peripheral surface portion 70 and a radially innermost surface portion 80, with both of said surfaces 70 and 80 being coextensive with the entire length of the tray.

The long bone reconstruction tray 60 has an elongate hollow void or passage 90 centered within said tray, and coextensive therewith to contain the bone graft materials. The tray has opposite ends 61 and 62 which are in a close juxtaposition relationship to form a narrow slit or space gap 63, through which the bone chips may be inserted. Alternatively, ends 61 and 62 may be in an abutting relationship or sutured together to form a closed circle.

A plurality of voids or apertures collectively designated by reference numeral function as pores. As in the case of the mandibular reconstruction tray 10, the pores may be of any shape, and the diameter of the pores might be greater than the distance between the pores. But other than that, the pores may be in any predetermined spaced apart relationship, to achieve optimum porosity consistent with rigidity and immobili zation of bone ends.

Although not shown here, the novel hollow mesh tray may be of any size or shape and may, of course, be suit able or adaptable for reconstructive surgery of a variety of bones.

Other plastic materials may be used in this novel manner, but a plastic tray made of either Dacron or Nylon mesh impregnated with a polyether urethane elastomer is preferred. The mesh is saturated with catalyzed urethane and the excess is removed by calendering between sheets of polyethylene. The impregnated mesh is then draped onto a solid model of the section to be reconstructed and contoured tightly around the model with the use of small spring clamps, or wooden clothes pins. The structure is then cured in a circulating oven at 200 F. for 6 hours. Following three days of further curing at room temperature, the implant is trimmed to size. It is sterilized by autoclaving.

It has been found that the alloplastic tray described herein has been well-tollerated in an experimental basis on animals. There have been no systemic effects observed and local tissue response has been minimal.

It should be noted that the material of which the tray is composed, need not be composed of Dacron or Nylon mesh but should be any material which has physical strength, optimal rigidity, simple fabricating technology, histocompatibility, and inertness.

After experimental testing of the novel invention described above, evidence for new bone formation was gathered radiographically, histologically, and by intravital tetracycline-labeling. Evaluation of the plastic tray at times of biopsy have revealed no changes in physical properties or evidence of chemical degradation of the plastic tray.

Thus it may be seen, that optimum conditions for bone induction are provided when a fresh, autologous graft of cancellous bone, rich in marrow and of appropriate particle size is applied to a well prepared host bed of bone. These conditions afford the likelihood that some of the transplanted tissue will survive and produce bone. Additionally, the transplant may cause the host cells to produce new bone by induction. Connective tissue cells which otherwise would not have shown osteogenic capability are induced to do so by the proximity of host to bone. A common clinical application of particulate bone grafting has been in the fusion of joints and to fill surgical defects. Applied to mandibular reconstruction, particulate grafting for bone induction in a non-metallic or alloplastic hollow mesh tray allows osteogenesis to occur across a gap which would not otherwise become bridged by a new bone. The configuration of the bone formed is guided by the implant tray, thus aesthetic considerations are possible. Of course, the usefulness of this novel technique may be considerably broadened by reconstructing osseous contour defects in other parts of the face, as well as in other areas of the body.

The structures and methods set forth above are merely illustrative and could be varied or modified, or of different forms or shapes to produce the same desirable results without departing from the scope of the inventive concept.

I claim:

1. A tubular, non-metallic tray adaptable for reconstruction of long bones, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising:

a substantially cylindrical outer peripheral surface portion, the opposite ends of which are in a close juxtaposition relationship to form a narrow slit, coextensive with the length of the tray, and

a radially innermost surface portion, the opposite ends of which "are in a close juxtaposition relationship and abut said narrow slit, said innermost surface portion coextensive with the outer peripheral surface portion, and adjacent to the elongate center passage.

2. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising:

a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality'of aspects, including a buccal aspect which has a narrow slit along the length of said aspect, and

two opposing ends of said tray, simulative of the ascending rami of said patient, the body of said tray being intermediate said opposing ends.

3. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising:

a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality of aspects, including an inferior aspect which has a narrow slit along the length of said aspect, and

two opposing ends of said tray, simulative of the ascending rami of said patient, the body of said tray being intermediate said opposing ends.

4. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising:

a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality of aspects, including a superior aspect which has a narrow slit along the length of said aspect, and

two opposing ends of said tray, simulative of the ascending rami of said patient, the-body of said tray being intermediate said opposing ends.

5. A non-metallic tray, adaptable for osseous contouring of the face, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising:

a shaped body simulative of the body of a normal facial area to be contoured of a particular patient, said shaped body having a plurality of aspects, including one aspect which has a slit along the length of said one aspect. 

1. A tubular, non-metallic tray adaptable for reconstruction of long bones, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising: a substantially cylindrical outer peripheral surface portion, the opposite ends of which are in a close juxtaposition relationship to form a narrow slit, coextensive with the length of the tray, and a radially innermost surface portion, the opposite ends of which are in a close juxtaposition relationship and abut said narrow slit, said innermost surface portion coextensive with the outer peripheral surface portion, and adjacent to the elongate center passage.
 2. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising: a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality of aspects, including a buccal aspect which has a narrow slit along the length of said aspect, and two opposing ends of said tray, simulative of the ascending rami of said patient, the body of said tray being intermediate said opposing ends.
 3. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising: a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality of aspects, including an inferior aspect which has a narrow slit along the length of said aspect, and two opposing ends of said tray, simulative of the ascending rami of said patient, the body of said tray being intermediate said opposing ends.
 4. A non-metallic tray, adaptable for mandibular reconstruction, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising: a body of the tray, simulative of the body of a mandible of a particular patient, said body having a plurality of aspects, including a superior aspect which has a narrow slit along the length of said aspect, and two opposing ends of said tray, simulative of the ascending rami of said patient, the body of said tray being intermediate said opposing ends.
 5. A non-metallic tray, adaptable for osseous contouring of the face, having a plurality of pores penetrating the thickness of the non-metallic material, and having an elongate center passage coextensive with the length of the tray, comprising: a shaped body simulative of the body of a normal facial area to be contoured of a particular patient, said shaped body having a plurality of aspects, including one aspect which has a slit along the length of said one aspect. 